8159Re: MARCH IBM PC 5150 rev A Restoration Project Notes
- May 23, 2008--- In email@example.com, "B. Degnan" <billdeg@...> wrote:
> Hi all.
> I have been able to get MARCH's IBM PC 5150 rev A up and running. I
> post detailed notes on my web site. This is the 16K-64K originalIBM PC
> model with original black power supply. Very rare rev "A" model andworthy
> of a museum.need to
> In summary
> -there is bad RAM, but I was able to get a 32K contiguous to function,
> enough to boot DOS 1.1, but not enough for DOS 2.x or higher. I
> find and replace the bad 4116 chip(s) so that the system is using afull 64K.
I should have a few of those if you want them, let me know.
> -BASIC ROM C 1.0 - (cassette basic 1.0). Note that with 32K RAM,
> still 28K available for BASIC. This is due in part to the CGA cardhaving
> it's own memory. I have a good article on the IBM PC in the CISC367color card.
> directory of my web site if you're interested in more details.
> -the original mono display card was bad, replaced with a CGA monitor
> card. Looking for a replacement monochrome. changed settings for
> -the one diskette works - switch settings OK
> -the dip switches indicated the presence of a 8077 co-processor, but
> was present. Changed switch to "no co-processor"Possibly the co-processor as well but i need to look.
> Pictures (not renamed yet, but re-sized)
> I am working on some sort of display for the MARCH exhibit of this
> More news soon. I took notes of the entire restoration "logic"
> NEXT: replace the RAM, find an IBM monochrome card. more cleaning.
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